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Observations on the diffuse thalamic projections

1955; Elsevier BV; Volume: 7; Issue: 4 Linguagem: Inglês

10.1016/0013-4694(55)90087-0

1872-6380

Blaine S. Nashold, John W. Hanbery, Jurek Olszewski,

Neurological diseases and metabolism

Extensive cortical ablations and focal lesions of the striatum were made in cats and monkeys, and the degeneration of the thalamic nuclei was studied in Nissl stain after survival periods of at least two months. Degeneration in the thalamus does not follow in an "all or nothing" manner. Between the extremes of entirely normal appearance and complete degeneration with loss of ganglion cells and heavy gliosis, there exist an array of intermediate changes. Their significance in the organization of thalamic efferents is discussed. Lesions restricted to the caudate nucleus or putamen did not produce degeneration in the thalamic nuclei. Lesions of the caudate nucleus which involved the adjacent portion of the internal capsule were followed by extensive cell loss and gliosis which involved the oral portion of the reticular nucleus, the nucleus ventralis anterior and the oral portions of the intralaminar nuclei. Lesions placed in different regions of the internal capsule and oral portion of the thalamus showed the presence of an anatomical rostral outflow. Cortical removals consisted of hemidecortication, either complete or limited to the isocortex. In addition to degeneration of the specific projection nuclei, marked changes were present in the intralaminar nuclei. The changes were observed after removal of the isocortex alone with varying amounts of damage to the underlying white matter. In complete hemidecortication, the extent of degeneration of the intralaminar nuclei was only slightly modified. The details of these findings are presented and their significance discussed.